title: The interaction of exercise ability and body mass index upon long-term outcomes among patients undergoing stress-rest perfusion single-photon emission computed tomography imaging.
abstract: BACKGROUND
  The obesity paradox has been reported in several populations of patients with cardiovascular disease. Recent data have shown that physical fitness may attenuate the obesity paradox. Patients who undergo pharmacologic stress testing are known to have a higher risk of mortality than those who can exercise. The purpose of this study is to determine the interaction of obesity and exercise ability on survival among patients with a normal stress-rest single-photon emission computed tomography (SPECT).
  
  
  METHODS
  A total of 5,203 (60 ± 13 years, male 37%) patients without a history of heart disease and a normal stress-rest SPECT between the years 1995 and 2010 were included in this analysis. Body mass index categories were defined according to the World Health Organization classification: normal weight, 18.5 to 24.9 kg/m(2); overweight, 25 to 29.9 kg/m(2); and obese, ≥30 kg/m(2). Patients were divided into 3 groups based on their ability to exercise: those who reached ≥6 METs on exercise, those who attained a level of <6 METs, and those who required pharmacologic stress. Patients in each of these fitness groups were further divided into 3 subgroups based on their body mass index.
  
  
  RESULTS
  There were 939 (18%) deaths during a mean follow-up of 8.1 ± 4.1 years, for an overall event rate of 2.3%/y. Both exercise to ≥6 METs and being obese were associated with lower mortality. Adjusted multivariate analysis using the obese high-fit patients as the reference showed a wide heterogeneity in annualized mortality rates according to exercise and weight status, with annualized event rates which varied from 0.6%/y in the obese subjects who were physically fit to 5.3%/y among healthy subjects who underwent pharmacologic stress testing (P < .001).
  
  
  CONCLUSIONS
  Stress mode and body weight impacted long-term survival in patients with a normal stress SPECT. The benefit of being physically fit was evident in all weight groups, as was the adverse effect of being unable to exercise. However, with regard to body weight, there was a paradoxical survival advantage for those patients who were overweight and obese, regardless of their exercise ability.
authors.affiliation: Division of Cardiology, Department of Medicine, St Luke's-Roosevelt Hospital Center, Columbia University College of Physicians and Surgeons, New York, NY 10025, USA. suretsky@chpnet.org
authors.forename: Seth
authors.initials: S
authors.lastname: Uretsky
authors.forename: Azhar
authors.initials: A
authors.lastname: Supariwala
authors.forename: Srinivasa
authors.initials: S
authors.lastname: Gurram
authors.forename: Sri Lakshmi Kala
authors.initials: SL
authors.lastname: Bonda
authors.forename: Naganath
authors.initials: N
authors.lastname: Thota
authors.forename: Prema
authors.initials: P
authors.lastname: Bezwada
authors.forename: Seema
authors.initials: S
authors.lastname: Manchireddy
authors.forename: Subu
authors.initials: S
authors.lastname: Nair
authors.forename: Randy
authors.initials: R
authors.lastname: Cohen
authors.forename: Alan
authors.initials: A
authors.lastname: Rozanski
mesh_terms: D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000175:diagnosis* / Q000401:mortality / Q000503:physiopathology; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000175:diagnosis* / Q000401:mortality / Q000503:physiopathology; D011379:Prognosis; D012146:Rest / Q000502:physiology*; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D015996:Survival Rate / Q000639:trends; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D014481:United States / Q000453:epidemiology